METZGER, K.A.*; HERREL, A: Inertial feeding in reptiles: the role of skull mass reduction

Kinetic inertial feeding is a stereotypic form of prey transport which is utilized to move large food items from the jaw tips into, and through the oral cavity. Once the food item is grasped in the jaws, the head and neck are rapidly thrusted backwards and the jaws are simultaneously opened, releasing the prey. Next, the head-neck motion is reversed and the jaws closed around the prey. Inertial transport is seen in varying degrees among reptiles, with many birds, varanid lizards and crocodilians using it as their primary intraoral transport mechanism. Various other lizards (such as teiids) tend to combine both inertial and lingual transport behaviors. Although the distribution of feeding repertoires among reptiles has been documented, the morphological and functional adaptations related to different intraoral transport strategies are less well known. However, it has been predicted that skull mass should be reduced, relative to the postcranial mass in inertially feeding reptiles (ie. allowing them to maximize the backward acceleration of the prey). To test this hypothesis, cranial and postcranial masses were recorded from skeletonized lizards and crocodiles. Additionally, skull masses were compared to known body masses as well as body masses derived from published regression formulas based on axial skeleton measurements. By analyzing the data in an explicit phylogenetic context, we test the hypothesis that a reduced cranial mass is an adaptation to an inertial feeding strategy in non-avian reptiles.